From: Sundar Palaniappan (sundar_palaniappan@hotmail.com)
Date: Sun Dec 22 2002 - 14:57:59 GMT-3
Sage,
Richard is correct.
If you want to prevent R1 from learning network 160.160.0.0, then you need
to apply a "distribute-list (#)in" under OSPFon R1. What this does is, R1
still receives the LSA for this network and perform the SPF calculation but
does not put this route in the route table due to the filter applied.
Assuming all 3 routers are in the same area, they would have a similar OSPF
database. You can't filter LSA's but can apply filters (only inbound) under
OSPF to prevent routes from entering the routing table.
--Sundar
>From: "Richard Hanks" <ccieingroup@hotmail.com>
>Reply-To: "Richard Hanks" <ccieingroup@hotmail.com>
>To: "Sage Vadi" <sagevadi@yahoo.co.uk>, <ccielab@groupstudy.com>
>Subject: Re: distribute-lists
>Date: Sun, 22 Dec 2002 11:50:02 -0500
>
>Hi Sage,
>CCO is right. The distribute-list here mentioned is "distribute-list 1 in"
>but
>not distribute-list 1 in serial 1/0". You can not use the interface
>distribute
>list on OSPF, it wouldn't work. So if you want to filter the 160.160.0.0/22
>on
>R1, you are supposed to do the commands on R1 but not R2. Try this one:
>
>Config on R1 here:
>
>distribute-list 1 in
>access-list 1 deny 160.160.0.0
>access-list 1 permit any
>
>I think it will work. But if your scenario need you to config on on R2, I
>think there must be another way. But I need more detail information about
>your
>scenario, such as the Stub or ABR or ASBR information.
>
>Richard Hanks
>----- Original Message -----
> From: Sage Vadi
> To: ccielab@groupstudy.com
> Sent: Sunday, December 22, 2002 5:20 AM
> Subject: OSPF: distribute-lists
>
>
> This is what CCO says:
>
> Q: Can I use the distribute-list in/out command with
> OSPF to filter routes?
>
> A: OSPF routes can't be filtered from entering the
> OSPF database. The distribute-list in command only
> filters routes from entering the routing table, but it
> doesn't prevent link-state packets from being
> propagated.
>
> ~~~ MY PROBLEM ~~~
>
> Diagram:
>
> R1
> |
> R2--R3
>
> R1 learns 160.160.0.0/22 from R2, R2 learns this from
> R3. Fairly simple right?
>
> I want to put a distribute-list inbound on R2's serial
> interface to prevent R1 from learning this
> route/network.
>
> Config on R2 here:
>
> distribute-list 108 in Serial1/0
> access-list 108 deny ip 160.160.0.0 0.0.3.255 any
>
> Problem:
>
> R1 still has the route in it's routing table!!! Doh!
> CCO says it should not be in the routing table, but it
> should be in the OSPF database.
>
> Q) Any tips/help/suggestions?
>
> rgds,
> Sage
>
>
>
>
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